1. Field of the Invention
The present invention relates to the field of emulation of hardware devices, more particularly the present invention relates to the emulation of input/output devices for a processor wherein the emulation is provided by the host processor to which the processor is connected to.
2. Background of the Invention
Processors and computer systems exist in a wide variety of sizes and capabilities. One popular type of computer system is referred to as a personal computer such as the IBM PC.RTM. and IBM PC/AT.RTM. (manufactured by IBM Corporation, Armonk, N.Y.), (IBM PC and IBM PC/AT are registered trademarks of International Business Machines Corporation) and compatibles such as that manufactured by Compaq Computers, Houston, Tex. Due to the popularity and widespread use of personal computers, a wide variety of software is available to run on personal computers however, personal computers are limited in their capability and functions and often users may find the need for a more powerful computer system. The type of computer system often referred to as a "workstation", is being used to fill that need. An example of computer workstations are those manufactured by Sun Microsystems Inc, Mountain View, Calif. However, due to the fact that the workstation typically uses a different processor then the PC as well as a different operating system and internal architecture, the applications written for the personal computers will not run on a workstation.
Some users have discovered the need to have the ability to run personal computer applications while maintaining the power of the workstation when necessary for other applications. Thus it is desirable to provide a single computer system that can run as a workstation as well as a personal computer. One method to do this is to emulate the operation of a personal computer on the workstation. However, this is achieved entirely through software and is extremely slow and quite burdensome to operate.
Another option is to provide the processor of the personal computer as a component of the workstation wherein the processor can operate its own operating system and execute processes and procedures as if it were operating in a stand alone personal computer. The workstation processor acts as the host processor and provides any peripheral support that the personal computer processor requires. Although an improvement over emulation, it is still quite slow in response and computationally intensive because each time the microprocessor, that is, the microprocessor or the "personal computer,", attempts to communicate with a peripheral device, the communication is sent to the host processor which must then interpret the communication and determine what kind of response is required. For example, if the process executing on the microprocessor attempts to write to an I/O device such as a disk drive, the host processor must provide the emulation of the disk drive because the microprocessor does not have a disk drive but rather utilizes the disk drive of the host computer system (e.g., workstation). As the host processor receives the request by the microprocessor to write information to the disk drive, it sends back the proper acknowledgement to the microprocessor and stores the information appropriately in its own disk drive. However, this process is also quite time consuming because the workstation processor must intercept the request, determine what device the request is directed to and determine what the proper response to the request should be in order to send back a response to the microprocessor.